The aim of our research was to verify selected methods to determine microbial activity during extraction process in term of speed, simplicity and accurancy of the analysis. Indirect methods – enzymatic determination of L-lactic acid, isotachophoretic determination of lactic acid, pH, as well nitrite amounts determination were verified. The results of these methods were compared with those of direct one – determination of bacteria counts (mesophilic and thermophilic bacteria). The determination of L-lactic acid by enzymatic device MICROZYM – L is very simple and rapid. But in same cases L-lactic acid does not indicate a true microbial situation in extractor. The determination of total lactic acid (L + D isomers) is more adequate for detection of contamination in extractor. The results of the nitrite amount determination did not confirm the sanitary situation found out by measurment of lactic acid, pH and bacteria counts in some cases.